I would like to use an external 3.0V reference for A/D conversions.Looking into the schematics, the related pin on the SAM3X8EA is connected to a (filtered) 3.3V supply. The AREF pin in the standard version of the board (mine is R3) is therefore simply a 3.3V output.On the other hand, the board seems to have a provision to make a simple change to allow to use the AREF as an input to the SAM3X8EA. There is a small white rectangle drawn on the upper side of the board, with the text "3.3/Ext" above and "AREF" on the right of it, nearby to the ICSP connector.Can anybody tell me what change has to be made?